1. Field of the Invention
The present invention relates to a wrench used for attaching and detaching, for example, a screw for fixing an automobile wheel.
2. Description of the Related Art
A cross limb wrench has been used for attaching and detaching a screw for fixing an automobile wheel, as disclosed in Japanese Unexamined Utility Model Registration Application Publication No. 51-74299.
The cross limb wrench includes a main shaft having a working portion such as a socket attached at the top thereof, which is fitted onto the head of a screw, and an operating handle disposed so as to perpendicularly intersect with the middle of the main shaft. In the case where the screw is to be fastened, when the working portion is set on the screw head and a turning force is then applied on the operating handle by one hand while the rear of the main shaft is lightly supported by the other hand, the main shaft is continuously turned with the inertia force of the operating handle so that the screw is quickly sent to its seating position.
Although the screw is fastened with up to a predetermined torque for the last time, when the screw is further fastened by still using the cross limb wrench, a torque of the cross limb wrench applied on the screw varies, thereby causing a risk that the screw is excessively fastened and consequently twisted off.
Conventionally, in order to avoid the above risk, when the screw is quickly sent to its seating position with the cross limb wrench as mention above, the cross limb wrench is replaced with a torque wrench having a screw-driver shape as disclosed in Japanese Examined Utility Model Registration Application Publication No. 39-12785 or an L-shape, and the screw is then fastened up to the predetermined torque.
Unfortunately, this method has problems because of the troublesome work for exchanging one wrench with another and the necesity of an additional storing place and cost for one of two kinds of wrenches required to be prepared.